1. Field of Invention
The present invention relates to a digital interface of an integrated subscriber line interface circuit for the connection of analog telephone subscriber lines of a digital time-multiplex telecommunications network, over which the setting up of various operating conditions of the subscriber line interface circuit is effected and the query of the results of the subscriber line status indications initiated in the subscriber line interface circuit takes place.
2. Description of the Prior Art
With the aid of integrated circuit technology, the space requirements for relatively complex electrical units have been constantlY reduced. A factor that will probably limit this trend is the number of plugs required for such an electrical unit, which, in view of connections that must be made, such as by soldering, cannot be arranged as close to one another as are desirable.
Known integrated circuits and in particular subscriber line interface circuits (SLIC's) are therefore equipped with a serial interface by means of which connections have various kinds of signals applied to them, and they are used to transmit various types of signals, such that the total number of required connections is relatively small in proportion to the number of the various types of signals to be received or transmitted, which results in a longer time in transmitting the signals. In addition, there is an increased circuit expenditure to manage the control of such a serial interface.
The primary object of the present invention is to provide an improved digital interface of the aforementioned type such that the number of connections is less than in prior art parallel interfaces, without the drawbacks of a serial interface.